Acceleration pump for carburetors



y 1937- Y. DJORDJEVITCH 3 ACCELERATION PUMP FOR CARBURETORS Filed Oct. 23, 1935 2 Sheets-Sheet l July 27, 1937. Y. DJORDJEVITCH A ACCELERATIC J N PUMP FOR GARBURETORS 2 Sheets-Sheet 2 Filed 001;. 23, 1935 RA 1 T VII/l/l/l/IIIIIl/Illl Patented July 27, 1937 ACCELERATION PUMP FOR, CABBURETORS Yesdimir Djordjevitch, Paris, France Application October 23, 1935, Serial No. 46,395 In France October 24, 1934 6 Claims.

It is known that carburetors provided with a pump show the drawback of feeding fuel through their pump, even when the throttle valve is wide open and the complementary feed provided by the pump is no longer useful.

My invention-has for its object to remove this drawback by means of an arrangement constituted by a part adapted to close the admission of fuel into the cylinder of the pump. This part of any suitable shape and material is yield- .ingly carried by the piston so as to remain in its position of closure as long as the piston has not receded sufficiently for moving said part away from its seat through the agency of an interposed part, which may be a spring or other yielding means completely expanded, which may occur for a predetermined position of the throttle valve.

I have shown by way of example in accompanying drawings several forms of execution of my invention.

Fig. 1 is a vertical cross section of the whole carburetor according to my invention,

Figs. 2, 3, 4 show different constructional modifications of the pump of which Figs. 2a,, 3a, or 312 and 4a are corresponding cross-sections.

Figs. 5 and 5a show modifications of the closure part, 7

Fig. 6 shows a pump having a hollow piston to which is applied an arrangement in accordance with my invention.

The carburetor shown in Fig. 1 comprises the usual elements, admission 'pipe A and float chamber B feeding the main spray nozzle L. The axis l of the throttle valve P, controlled in the usual manner by the accelerator pedal carries the lever 2 controlling the displacements of the piston 3 of the pump in the cylinder 8. 'The latter is provided at its lower end with an admission port ll) opening into the channel 9 constituted for instance by the usual channel connecting the float chamber with the main spray nozzle while the upper part of the said cylinder opens into the channel ll feeding the spray nozzle 5 of the pump. 7

At the lower part of the piston head is a stud 4 to which is secured the spring 6 carrying the valve 1 adapted to close the port [0.

When the throttle valve is sufliciently closed and the piston approaches its higher dead centre or is at thiscentre as shown in Fig. 1, the spring 6 is no longer stressed andthe valve has moved away from its seat and uncovered the port It). Consequently the fuel enters the chamber of the .pump in which the receding motion of the piston has produced a certain depression. The fuel passes then through the channel ll towards the spray nozzle 5. When the throttle valve is opened, the piston sinks and at a certain point it applies the valve 1 against its seat while compressing more or less the spring 6. It is apparent that the displacement of the piston underneath the position for which the valve comes into contact with its seat cannot cause any injection of fuel into the spray nozzle 5 as the fuel cannot enter the pump and'feed it any more through the port it. Of course the cylinder chamber being full of fuel when the valve comes into contact with its seat, the fuel is expelled by the first downward motion of the piston through a contrivance disclosed hereinbelow. Consequently when the amount of opening of the throttle valve is above a given value, the working of the pump causes, after this first load of fuel is expelled, no subsequent forcing of fuel through the spray nozzle 5 as long as the pump is not fed again with fuel. i

Fig. 2 shows the piston of the pump of Fig. 1 at the end of its downward stroke after compression of the spring 6. This same figure shows clearly, in combination with Fig. 2a, the groove E provided vertically in the wall of the cylinder; the groove E which instead of being vertical may be oblique or incurved, connects the opening of the channel I! in the cylinder with the clear- .ance it at the bottomof the latter. This groove is intended for allowing the passage, during the whole downward stroke of the piston, of the fuel contained in the pump and forced out under the action of the piston towards the spray nozzle 5 of the pump, as already stated.

On the other hand this same groove allows the passage of air during the to and fro motions of the piston and in particular during its upward stroke towards its upper dead centre. It should be. noted that in the arrangement of Figs. 1 and 2 and by reason of the perfect fluid tightness obtained during the closure of the valve between the pump and the float chamber, the spray nozzle 5 of the pump may open into the zone of depression itself. In fact during this closure of the valve, the piston moves only in the inoperative zone of reciprocation provided between the points corresponding to a predetermined opening of the throttle valve and to the maximum opening thereof, without exerting any action on the feeding of the spray nozzle.

In Fig. 3 the arrangement of the groove E is modified inasmuch as it is provided on the piston where it may appear under difierent shapes, such as those shown in cross-section in Figs. 3a and 31). Of course a suitable guiding of the piston rod, to which may be given for instance a square cross section, is required in order that the groove C thus provided in the piston remains in front of the channel i l opening into the cylinder. I have also shown, although this arrangement may be applied as well to any other form of execution, one or more transversal channels a connecting directly the cylinder with the float chamber, said channel a being uncovered by the piston during its upward stroke in order'to provide means for a speedier filling of the pump. This channel a may be given any desired shape allowing both the feed of fuel into the pump and the escape of air into the float chamber.

On the other hand, the escape of air through the spray nozzle may be furthered by means of a downwardly directed channel d opening into the channel i l and communicating with horizontal channels 0 opening in the pump cylinder for returning thereto the particles of liquid fuel carried along -by the air passing through I I: this is illustrated in Fig. 2.

The groove shown in Fig. 3 may moreover in the case of a hollow piston be replaced by a longitudinal slot.

In Figs. 4 and 4a the arrangement of the groove shown at D is again different. In this case it is annular so as to provide a moreconsiderable cross sectional area. It could of course as well be only partly annular. This annular space may be provided on the piston or in the cylinder.

The port-closing part may be of any material and may affect numerous different shapes. In all cases it may form a flap valve, a valve, a needle valve or else it may be constituted by a plastic obturator secured to the surface of the piston for instance through the agency of a tubular part surrounding it; in this latter case the port-closing part forms at the same time the yielding intermediary part used as a connection with the piston.

An advantageous form of execution is that of the type illustrated in Fig. 5 where the yielding intermediary part carrying the port-closing part is carried directly by the piston inside a chamber provided for this purpose or inside a sheath l2 rigid with the piston, the port-closing part being constituted by a rod I i sliding during the reciprocation of the piston inside this chamber or inside this sheath.

This rod i4 is applied, as soon as the piston has reached a predetermined point of its stroke against its seat formed by the fuel feeding port Ill. Thus from this moment onwards the rod begins sliding inside in its guiding chamber or sheath and compresses the coil spring l3 or other intermediary yielding part. The rod will then serve up to the end of the downward stroke of the piston as an abutment for the crushing or compressing of said intermediary part stretched between the upper part of the sheath or chamber, i. e. the bottom of the piston and the collar forming the head of the rod l4.

During the return of the piston to its upper dead centre, the rod M which closes the port either directly as a needle valve or with the interposition of a packing carried by it (Fig. 5a) will remain applied against its seat under the action of the spring it which will expand gradually as the piston rises. At the predetermined above mentioned point of the piston stroke, the spring l3 ceases expanding and the piston carries the rod I4 along with it, which uncovers the port [8 feeding the pump.

In Fig. 6 the arrangement is the same as in Figs. 1 and 2 except in that the invention is applied to a hollow piston to the bottom of which is secured the stud to which is attached the inner end of the spring 6.

Of course the relative arrangement and the shape of the parts as well as the manner of controlling the piston through pulling or pushing and the form of execution of the carburetor parts exterior to the pump may be modified in any suitable manner without widening the scope of my invention.

The field of application of my invention is not limited to carburetors but may be extended wherever it is required to handle or transport a fluid of any kind under conditions similar to those described and chiefly to cover or uncover an admission of fuel or of an oxidizing agent.

Similarly the different forms of execution described are applicable to downflow carburetors in which case the different parts are reversed in principle with reference to those illustrated without widening thereby the scope of my invention.

What I claim is l. A carburetor accelerating pump including a pump cylinder, a pump piston slidable therein, means for controlling same, spraying means opening into the upper part of the pumping portion of the pump cylinder, means for feeding fuel to the pump, opening into latter through the lower end thereof and elongated yielding means adapted to close said feeding means, secured through its upper end to the lower free end of the piston and adapted when freely expanding to occupy nearly the whole height of the pump cylinder with the piston at its upper dead point.

2. A carburetor accelerating pump including a pump cylinder, a pump piston slidable therein, means for controlling same, spraying means opening into the upper part of the pumping portion of the pump cylinder, means for feeding fuel to the pump, opening into latter through the lower end thereof, a flap valve adapted to close said feeding means, and. a yielding connection engaging through one end the flap valve, secured through the other to the lower free end of the piston and adapted when freely expanding to occupy nearly the whole height of the pump cylinder with the piston at its upper dead point.

3. A carburetor accelerating pump including a pump cylinder, a pump piston slidable therein, means for controlling same, spraying means opening into the upper part of the pumping portion of the pump cylinder, means for feeding fuel to the pump, opening into latter through the lower end thereof, a flap valve adapted to close said feeding means, a yielding connection engaging through one end the flap valve, secured through the other to the lower free endof the piston and adapted when freely expanding to occupy nearly the whole height of the pump cylinder with the piston at its upper dead point and means providing a throttled communication longitudinally of the lowered piston between the fuel feeding means and said spraying means.

4. A carburetor accelerating pump including a pump cylinder, a pump piston slidable therein, the lower end of which is deeply recessed, means for controlling same, spraying means opening into the upper part of the pumping portion of the pump cylinder, means for feeding fuel to the pump, opening into latter through the lower end thereof, a flap valve adapted to close said feeding means, a sheath carried axially by the lower end of the piston nearly throughout the height of the recess, an elongated carrier for the flap valve adapted to slide inside said sheath and to project beyond same to a maximum length which measured from the lower end of the sheath to the lower end of the flap valve is nearly equal to the maximum height between the lower end of the sheath and the opening of the fuel feeding means and yielding means located inside the sheath, engaging through one end the carrier and secured through the other to the bottom of the sheath including the part of the piston recess enclosed thereby and adapted when completely expanded to make the elongated carrier project to its maximum length beyond the sheath.

5. In a carburetor as claimed in claim 1 combined with a float chamber, the provision of a direct connection between the pump cylinder and the float chamber.

6. A carburetor accelerating pump including a pump cylinder, a pump piston slidable therein, means for controlling same, spraying means opening into the upper part of the pumping portion of the pump body, means for feeding fuel to the pump, opening into latter through the lower end thereof, a flapvalve adapted to close said feeding means, a yielding connection engaging through one end the flap valve, secured through the other to the lower free end of the piston and adapted when freely expanding to occupy nearly the whole height of the pump cylinder with the piston at its upper dead point, means providing a throttled communication longitudinally of the lowered piston between the fuel feeding means and said spraying means, and means for by-passing the fuel between the spraying means and the lower part of said throttle means.

YESDIMIR DJ ORDJEVITCH. 

